The apparent assassination of the estranged half-brother of North Korean leader Kim Jong Un is drawing the world's attention to the secretive Kim family's inner circle.

Kim Jong Nam, 45, died en route to a hospital Monday after he was reportedly poisoned by two women at Malaysia's Kuala Lumpur International Airport while waiting to take a Macau-bound flight, according to Malaysian and South Korean officials. Malaysian police have detained two women and one man in connection with the death. Authorities are hunting for other suspects.

FILE - This image provided by Star TV of closed circuit television footage from Feb. 13, 2017, shows a woman, left, at Kuala Lumpur International Airport in Sepang, Malaysia, who police say was arrested Wednesday in connection with the death of Kim Jong Nam.

Selangor Police Chief Abdul Samah Mat told VOA Friday the hospital has not released final results of an autopsy that could determine the cause of the death. Abdul Samah, who is in charge of the investigation, said the police are trying to obtain DNA samples from the victim’s kin to confirm his identify.

According to South Korean lawmakers briefed by the National Intelligence Service, there is reason to believe that Kim was killed on the orders of his younger half-brother Kim Jong Un, who is known to execute or depose anyone who appears to be a threat to the legitimacy of his rule. In late 2013, the North Korean leader executed his uncle Jang Song Thaek, who was widely deemed as the second-most powerful figure in the country.

Jang Jin-sung, who worked as a psychological warfare officer for North Korea's ruling Workers' Party before he defected in 2004, told VOA that given Kim Jong Nam's place as the firstborn child of Kim Jong Il, Kim Jong Un might have seen his brother's existence as an obstacle to his grip on power.

Kim Jong Nam is the eldest son of the late North Korean leader Kim Jong Il, who ruled the communist state from 1994 to 2011, and was once regarded as heir apparent to his father. The son was born on May 10, 1971. His mother was a South Korea-born film star, Song Hye Rim, who divorced her husband to become Kim Jong Il's secret mistress.

"Kim Jong Il wanted a family with the woman he loved, and now he had an heir, but he also needed to protect his position as his father's successor," reads an unpublished memoir obtained by VOA and based on the oral accounts of Li Nam Ok, Song's niece.

Kim Jong Il kept the relationship with Song secret, especially from his father Kim Il Sung.

Kim Jong Il almost completely insulated his son from the outside world. Li Nam Ok was his only playmate in Pyongyang. Kim, besotted with his son, forgave his "tantrums and capriciousness," according to French author Imogen O'Neil, who worked with Li on the memoir. Li left North Korea in 1992 and never returned.

"His father refused him nothing; Kim Jong Il used to say there was only his son in his life," according to O'Neil's manuscript.

The memoir offers a rare glimpse into Kim Jong Nam's childhood, adolescence and early manhood. It revealed that he lived in luxury in Pyongyang, surrounded by expensive goods virtually unseen in North Korea. His aunt, Song Hye Rang, who was Li's mother, oversaw Kim's private education, which covered math, science, English and Russian. When Kim was 8 years old, he visited Moscow, where his mother was receiving medical treatments.

According to the memoir, Kim Jong Il decided to send the "little general" overseas for "structured education" on his son's 10th birthday. For most of the 1980s, Kim Jong Nam lived in Switzerland, where he studied at the International School of Geneva.

After returning to Pyongyang in 1988, Kim, who was known to be a computer enthusiast, held government posts. At one point, he was head of North Korea's Computer Committee where he was in charge of developing information technology.

Yoji Gomi, a senior staff writer at the newspaper Tokyo Shimbun closely followed Kim Jong Nam and published a book in 2012 that was based on correspondence with him. Gomi told VOA that upon returning from Switzerland, Kim had frequently advised his father to adopt the free market system to boost North Korea's economy.

"Kim told me that he had some friction with the supreme leader Kim Jong Il, and that's when their relationship began to sour," Gomi said. "I believe that because of that friction, Kim was not able to become North Korea's leader and, instead, he led an itinerant life" outside North Korea.

Cheong Seong-chang, an expert on North Korea's leadership and director of unification strategy at the Sejong Institute in Seoul, said Kim Jong Nam was sidelined from succession when Kim Jong Il's third wife, Ko Yong Hui, a dancer born in Japan, gave birth to two sons, one of whom now rules North Korea.

"It appears that after Kim Jong Chul and Kim Jong Un were born, Kim Jong Nam may have come as a burden to Kim Jong Il," the analyst said in an email to VOA. Kim Jong Chul was last seen in 2015 in London at an Eric Clapton concert, according to press reports.

Some suspect that Kim Jong Nam fell out of favor with his father when he was arrested at Tokyo's Narita Airport in 2001 as he attempted to enter Japan with a forged Dominican Republic passport. He told police at the time that he had traveled to Japan to visit Tokyo Disneyland with his four-year-old son and two unidentified women.

Since then, Kim Jong Nam had been living in exile — mostly in Beijing and Macau — with his wife and children. Often spotted at hotels, casinos and airports throughout Southeast Asia, Kim was widely known for his gambling and drinking habits.

In an interview with TV Asahi in 2010, shortly before his younger brother Kim Jong Un rose to power, Kim Jong Nam expressed his discontent with the Kim family's three-generation dynasty.

In 2012, Kim Han Sol, the then 16-year-old son of Kim Jong Nam, said during an interview with a Finnish TV channel that he didn't know how his uncle Kim Jong Un "became a dictator."

Feared for his life

Seoul's intelligence agency said Kim Jong Un had "a standing order" for his half-brother's assassination and that there had been a botched attempt in 2012, according to South Korean lawmakers briefed by the agency.

Following the failed attempt, Kim Jong Nam begged for his life in a letter addressed to Kim Jong Un, said the lawmakers.

Kim Jong Nam's family members are believed to be in Beijing and Macao under China's protection, according to the South Korean intelligence agency.